During physical exercise the stress level a person's nervous muscular system experiences varies. In order for the exercise to be effective, it is good to know what kind of physical stress a person's nervous muscular system or some part of it has undergone during the exercise. In addition to the stress level, it is good to know the person's recovery from the performed exercise, whether it is a question of a top athlete or a person keeping fit. If the person does not recover from the performed exercise, he may due to excessive exercise end up in a state of overtraining. This may lead to mandatory resting, which may last from weeks up to months. Especially for top athletes a state of overtraining due to exercise is a very undesired phenomenon.
A person's own subjective sensation of stress and recovery therefrom has been found to be insufficient.
There are various measuring arrangements for measuring the fitness state of an exercising person. The aerobic fitness, i.e. the fitness associated with the heart, lungs and circulation, describes the amount of oxygen pumped by the heart and transported to the muscles and the ability of the muscles to utilise the oxygen they receive. The aerobic fitness is especially associated with endurance sports.
A heart rate monitor with its heart rate analysis can for example be used for measuring aerobic fitness. Heart rate analysis is used to measure the effect of many bodily occurrences on the heart rate, which is regulated by the autonomic nervous system. The regulation of the autonomic nervous system can be disturbed due to hard exercise or psychological stress. A serious state of overstrain caused by exercise can be seen in the autonomic nervous system also during rest.
In the autonomic nervous system the stress and overtraining are often only seen with a delay, wherefore the strain of the exercise may have been too straining for a long time, before the situation is observed. Thus correcting procedures may take time.
One way to measure a person's fitness and recovery is to sufficiently often do blood tests in connection with exercises or after them. Such a measuring method is however difficult to utilise. Additionally measurements performed from blood are complex and expensive to perform for a common person keeping fit.
Recovery can be measured with extensive blood tests, which measure for example lactate and creatine kinase. Lactate is a product of glucose metabolism, which is produced in the muscles especially as a result of anaerobic muscle work. Creatine kinase is a common enzyme in muscle cells.
When a muscle is damaged due to exercise or some other reason, creatine kinase is released from the muscle cells into the blood. The larger the damage, the more the measuring value of the creatine kinase measured with a blood test rises. Similarly, if an untrained person suddenly uses his muscles vigorously, the associated muscle pain and mild muscle damage increases the measuring value of the creatine kinase.
In order to optimise the end result of the exercise, the person performing the exercise must find the right ratio between exercise and recovery. Thus tiredness and tissue damage caused by hard exercise is prevented. Depending on the degree of difficulty of the exercise, the person performing the exercise on average needs a time period of two days to two weeks to recover from a straining exercise.
Supercompensation is a change generated by training and recovery therefrom in the performance of an athlete, as a result of which the performance is momentarily above the normal level. A well-timed new exercise thus provides a rising development in the performance of the person performing the exercise.
Both the performed exercise and the recovery from the exercise, in practice the rest, have an important part in the phenomenon of supercompensation. An exercise taking place too early or being too hard before the recovery from the last exercise leads to a state of overtraining. In order to achieve the state of supercompensation the person performing the exercise must optimise his exercise so that the recovery time from the last exercise is not too long or too short.
Various treatment devices based on electrical stimulation are used for treating a damage or imbalance in the nervous muscular system arisen as a result of illness, injury or over exercise. The treatment device is used to lead electric current into the part of the nervous muscular system to be treated.
For example Finnish patent FI 120575 describes an electric treatment device and treatment arrangement, by using which the electricity treatment given to a patient can be made more effective. In the method described in patent FI 120575, the most suitable frequency of the treatment current and the most suitable strength of the treatment current for the patient are first determined. When these variables are determined, these variables are used to treat the patient's muscle damage. The aim of the treatment is to with the aid of electricity treatment return the metabolism of the object being treated, for example a certain muscle, to a level, which corresponds to the metabolism of a healthy muscle. The success of the treatment is indicated by the fact that a treatment current of a certain frequency reaches some predetermined threshold value. The method can thus speed up the improvement of the nervous muscular system being treated.
Other various devices and methods suited for treatment of the function of either nerves or muscles are presented in the following publications: CN 1029505, CN 101612450 and U.S. Pat. No. 7,254,444. The references describe methods and devices, which can be used to treat either damaged or overstressed tissues in the body.
Recovery is a result of partly nervous and partly metabolic factors. There has so far not been a reliable method of measuring anaerobic recovery or state of acute recovery of nerves and muscles without extensive blood tests.